// Copyright 2022 ByteDance and its affiliates.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package registry

import (
	"net/http"

	"github.com/prometheus/client_golang/prometheus"
	"github.com/prometheus/client_golang/prometheus/promhttp"
	"k8s.io/component-base/metrics"
)

var (
	defaultRegistry = metrics.NewKubeRegistry()
	// DefaultGatherer exposes the global registry gatherer
	DefaultGatherer metrics.Gatherer = defaultRegistry
)

func init() {
	RawMustRegister(prometheus.NewProcessCollector(prometheus.ProcessCollectorOpts{}))
	RawMustRegister(prometheus.NewGoCollector())
}

// Handler returns an HTTP handler for the DefaultGatherer. It is
// already instrumented with InstrumentHandler (using "prometheus" as handler
// name).
//
// Deprecated: Please note the issues described in the doc comment of
// InstrumentHandler. You might want to consider using promhttp.Handler instead.
func Handler() http.Handler {
	return promhttp.InstrumentMetricHandler(prometheus.DefaultRegisterer, promhttp.HandlerFor(defaultRegistry, promhttp.HandlerOpts{}))
}

// Register registers a collectable metric but uses the global registry
func Register(c metrics.Registerable) error {
	err := defaultRegistry.Register(c)
	return err
}

// MustRegister registers registerable metrics but uses the global registry.
func MustRegister(cs ...metrics.Registerable) {
	defaultRegistry.MustRegister(cs...)
}

// RawMustRegister registers prometheus collectors but uses the global registry, this
// bypasses the metric stability framework
//
// Deprecated
func RawMustRegister(cs ...prometheus.Collector) {
	defaultRegistry.RawMustRegister(cs...)
}

// CustomRegister registers a custom collector but uses the global registry.
func CustomRegister(c metrics.StableCollector) error {
	err := defaultRegistry.CustomRegister(c)

	//TODO(RainbowMango): Maybe we can wrap this error by error wrapping.(Golang 1.13)
	_ = prometheus.Register(c)

	return err
}

// CustomMustRegister registers custom collectors but uses the global registry.
func CustomMustRegister(cs ...metrics.StableCollector) {
	defaultRegistry.CustomMustRegister(cs...)

	for _, c := range cs {
		prometheus.MustRegister(c)
	}
}
